Pump



Sept 9, 1947- B. w. MANTLE 2,427,060

PUMP

Filed June 26, 1944 21 Sheets-Sheet 1 IN VEN TOR.

Burr Wlanle ATTORNEYS Sept. 9, 1947. B. w. MANTLE PUMP Filed June 26, 1944 2 Sheets-Sheet 2 TTOQNEYS Patented Sept. 9, 1947 PUMP Burr W. Mantle, Pittsford, N. Y., assignor to American Brake Shoe Company, Wilmington, Del., a corporation of Delaware Application June 26, 1944, Serial No. 542,127

This invention relates to pumps for pumping air or gas and more particularly to the unloading of such pumps when the pumping action thereof is to be suspended.

Air or gas pumps of the kind to which this invention relates may .be utilized for different purposes such as the production of a supply of compressed air or the evacuation of air or the like to4 produce a reduced pressure or partial Vacuum. J

In many instances such pumps are continuously operated as, for example, where such a pump serves as an air compressor used in connection with paint spraying equipment, it being advantageous so to do since this avoids frequent starting and stopping of the pump. In such an instance, however, it has been found to' be desirable to unload the pump when the desired pressure condition has been produced by the pump. Thus, for example, when the supply of air under pressure in a supply tank or thel like has been built up by such a pump to the desired pressure level it is desirable to suspend the pumping action of the pump. Among ways in which it has been proposed heretofore to thus unload or suspend the pumping action of a pump or compressor in such and related circumstances has been to close oi the inlet to the pump so that as the pump continues to operate with the inlet so closed, and when this is done a Vacuum is created in the cylinder head or heads in the pump. This, however, has been found to be disadvantageous because, among other reasons, when a vacuum is created in the cylinder head or heads in this manner, the pressure in the crank case of the pump has been effective to force the lubricant past the piston or pistons of the pump into the cylinder head or heads and, particularly in the case of pumps used as air compressors in connection with paint spray equipment, the presence of lubricant in the cylinder head or heads is objectionable since such lubricant may become mixed with the air being discharged from the compressor.

However, since an expeditious way in which to unload a pump is to close off the inlet thereto, it is among the objects of my invention to enable a pump to be unloaded by closing oif the inlet thereof but to, at the same time, avoid the likef lihood that lubricant will be forced into the cylinder head or heads of the pump.

It has recently become customary in the compressor art to resort to a so-called sealed crank case and the present invention is particularly adapted for use with a compressor embodying Claims. (Cl. 5530-30) 2 such a crank case since it is among the objects of my invention to equalize pressure on opposite sides of a piston operating in a cylinder of a pump or compressor when such pump or compressor is unloaded by closing off the inlet thereto, and objects ancillary to the foregoing are to establish an interconnection between the inlet leading to a cylinder head of a pump or compressor and the crank case thereof of the closed or sealed type so as to enable a vacuum to be created in the crank case simultaneously with the creation of a vacuum in the cylinder head when the inlet to the pump or compressor is closed off; and to insure that when air is withdrawn from the crank case of a pump or compressor under the aforesaid circumstances, lubricant from the crank case will not -be drawn into the cylinder head of the pump or compressor through the aforesaid interconnection.

Further and more specific objects of the present invention are to establish intercommunication between the portion of a pump or compressor leading to an inlet valve thereof and the sealed or closed crank case of the pump or compressor by opening communication into the crank case adjacent to one of the bearings for the crank shaft so that air withdrawn from the crank case will flow through such bearing; and to utilize a tapered roller bearing in such position that air withdrawn from the crank case in the course of unloading the pump or compressor will flow through such tapered roller bearing to thereby have entrained lubricant and the like removed therefrom prior to the time the air passes through the inlet valve and cylinder head of the pump or compressor.

Still further objects of the invention are to utilize pressure responsive means for controlling' operation of the means effective to bring about unloading of a pump or compressor by closing oi the inlet thereof; to normally urge means effective to close olf the inlet of a pump or compressor into open position; and to move such means into closed position when a predetermined pressure condition has been established in the supply tank with which the pump or compressor is associated.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawing which, by way of illustration, shows preferred embodiments and the REESSU the invention embodying the same or `equivalent prlnciple may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In'the drawing:

Fig. 1 is an end elevational view illustrating the invention as embodied in an air compressory system, certain parts being broken away to illustrate the novel apparatus of the present invention;

I the invention as embodied in an apparatus for producing a. vacuum,

-For purposes-of disclosure, the invention is illustrated'in-Fig's. 1 to 3 of the drawings as embodied in an air compressor system having a two-stage compressor, b ut it will be understood that my invention is suitable for use either with a single stage compressor or with any other arrangement of a multiple stagecompressor or other pump, in accordance with my invention, when the pump or compressor is to be unloaded, communication is shut oi between the intake and the cylinder of the single stage pump, or between the intake and the cylinder of the first stage of a multi-stage pump. A

Referring to Figs. 1 to 3 of the accompanying drawings, the compressor embodies a crank case which is desirably of the closed or sealed type. Bearings 6 and 1 are provided in the crank case 5 and the crank shaft 8 is journaled in these bearings. In this present instance the power or driving means for the pump is disposed outside of the crank case, and an extension 9 of the crank shaft 8 is accordingly extended outwardly of the bearing 6 through a suitable shaft seal I0 mounted in the crank case 5 outwardly of the bearing 6 and which is effective to prevent flow of air-into and from the crank case 5 past the extension 9 of the crank shaft 8. In the present instance a pulley is mounted on the extension 9 of the crank shaft outwardly of the crank case 5 and a belt I2 is passed about the pulley I| and leads to a suitable source of power such as an electric motor, whereby the crank shaft 8 may be set in rotation when the compressor is to be operated.

In the illustrated compressor the rst stage is aiorded by the cylinder |3 and the second stage is afforded by the cylinder I4, the piston |5 being reciprocal in the cylinder |3'and the piston I5 being reciprocal in the cylinder |4, such pistons being connected to the throws of the crank shaft 8 respectively by the connecting rods I1 and A casing generally indicated by I9 includes an air inlet passage 20 from which a passage 2| leads to the intake valve 22 (which is partially diagrammatically illustrated in Fig. 2) of the cylinder I3. The outlet passage 23 leads from the outlet valve 24 of the cylinder I3 (which outlet valve is also partially diagrammatically illustrated) to one end of the inter-cooler 25 which in turn leads to the inlet valve 26 of the cylinder I4. The outlet passage 21 leads from the outlet valve 28 of the cylinder |4 to the uid discharge line 29 which leads to a storage tank T or the like where air under pressure is stored the valves 26 and 28 also being partially diagrammatically illustrated.

It should be observed that the pressure in the tank T is maintained by the valves as 28 of the compressor, such valve means serving in effect as check valve means in a known manner.

A valve seat 30 is provided at the free end of the inlet passage 20 and a valve member 3| is adapted to cooperate therewith so that when the valve member 3| is engaged with the valve seat 38, flow through the inlet passage 20 is closed ofi. The valve member 3| includes a stem 32 that is extended through and supported by a bearing 33 carried by a bracket 34 in the casing I9. A shaft 35 extends across and is carried by the casing I9 and supports a three armed lever L for rocking movement in the casing |9. The arm 35 of this three arm lever L is connected to the stem 32 of the valve member 3| by a suitable yoke connection 31, while the arm 38 of this three arm lever extends beneath a housing 39 formed on the casing I9. A link 40 is pivotally connected to the free end of the arm 38 and carries a spring pad 4| against which one end of a spring 42 bears. The spring 42 is mounted within the housing 39 and the opposite end thereof bears against a spring pad 43 carried` by a screw stud 44 which is mounted in a tapped opening provided at the upper end of the housing 39, the screw 44 thereby being extended outwardly of the housing 39. A lock nut 45 cooperates with the screw 44 and the adjacent end of the housing 39 to secure the screw 44 in adjusted positions.

A domed pad 46 is provided on the casing I9 and the means which secure this pad in position is also effective to secure a diaphragm 41 in position in the casing |9, the pad and vdiaphragm cooperating to dene a pressure chamber 48 to which an inlet passage 49 is directed. A stud 50 on the diaphragm 41 bears on the arm 5| of the three arm lever L, and when a predetermined pressure is built up in the chamber 48, this stud 50 is effective on the arm 5| and through the arm 36 of the lever L to urge the valve member 3| into engagement with the valve seat 30 to thereby shut off flow through the inlet passage 20. Normally, however, the spring 42 is effective on the arm 38 to urge the valve member 3| away from the valve seat 30 to thereby permit flow through the inlet passage 2U. The screw 44 is disposed in such adjusted position that the spring 42 is rendered effective to maintain the valv member 3| unseated from the valve seat 30 uiitin a predetermined pressure has been built up in the chamber 48.

An inlet pipe 52 leads to the interior of the casing I9 from, in the present instance, a combined air filter and muffler 53 and the valve member 3| is disposed between the inner end of the pipe 52 and the passage 20 so that when the valve member 3| seats on the valve seat 30 flow of air to the passage 20 from the lter and muiller is shut on.

A cap 54 is mounted on the end of the crank case 5 outwardly of housing or the bearing 1 and is effective to seal and close this end of the crank case 5. A pipe 55 leads from the interior of the cap 54 to the inlet passage 20, opposite ends of this pipe 55 being secured in position by suitable ttings 56 and 58. The pipe 55 opens into the inlet passage 20 behind the valve seat 3D so that when the valve member 3| is engaged with this valve seat, flow of air from the pipe 52 to the pipe 55 is closed off. However, when the valve member 3| is disengaged from the valve seat 30, air may ow from the pipe 52 through a passage 20 and pipe 55 into the cap 54 and thence into the crank case 5. whereby a breathing arrangement for the crank case is aiorded.

It will be noted that the anti-friction bearing 'I as herein shown is of thehtapered roller bearing type and I have found itA advantageous to resort to a bearing this character and to provide a cap as 54 or other connection to the interior of the crank case 5 adjacent to such a bearing for so to do insures that air withdrawn from the interior of the crank case 5 and up through the pipe 55 will flow through the tapered roller bearing 1. As the air ows through such a tapered roller bearing, entrained lubricant or the like is eiectively removed therefrom so as to thereby be prevented from passing to the inlet passage 2U and thence into a cylinder as I3. Thus the anti-friction bearing as 1, in effect, serves as a means for ltering or removing lubricant from the air that passes therethrough.

In the present instance a pipe 58 leads from the inlet passage 49 to the tank T to which the discharge pipe 29 is connected, and thereby a connection is established between the storage receptacle as the tank T and the chamber 48. Therefore, when a predetermined pressure is attained in the tank T and it is advantageous to unload the compressor, the predetermined pressure will be effective on the diaphragm 41 to overcome the effect of the spring 42 and thereby cause the valve member 3| to seat on the valve seat 30. This shuts off ow of air through the inlet passage 20 and as the piston I5 continues to reciprocate in the cylinder I3 a vacuum is drawn in this cylinder. Moreover, such reciprocation of the piston I5 in the cylinder I3 withdraws air from 'the interior of the crank case 5 through the bearing 1, the interior of the cap 54 and pipe 55, whereby a vacuum is drawn in the interior of the crank case 5, such vacuum bein-g created simultaneously with the creation of a vacuum in the head `of the cylinder I3. Furthermore, when the valve member 3| seats on the valve seat 30 the supply of air to the second stage of the illustrated two stage compressor is also closed olf so that immediately after a vacuum is created in the head of the cylinder I3 a vacuum'is also created in the head of the cylinder I4. However, by the time a vacuum is created in the heads of these cylinders a vacuum will also be created in the crank case 5, `wherefore pressure on opposite sides of the pistons I5 and I6 is equalized so that there is no tendency for lubricant to be forced up past the pistons and into the heads of the cylinders I3 and I4, and I have found that this arrangement is effective to insure against lubricant collecting in the heads of the cylinders when the compressor is unloaded by closing off the inlet thereof.

It has been pointed out hereinbefore that the present invention may be utilized in connection with pumps other than compressors, and one such instance is found where a pump is being used to produce vacuum or low pressure. Thus,

in Fig. 4 of the drawings I have illustrated an' embodiment of the invention that comprises a two-stage pump 60 generally similar to the compressor shown in Figs. 1 to 3. and the pump 60 is associated with a vacuum tank TV to withdraw air from the tank and thereby establish a low pressure or vacuum in the tank TV. In' most of its structural features the pump 50 is similar to the compressor of Figs. 1 to 3, and similar refence characters are employed as to such corresponding parts of the pump 6|). It will be observed, however, that the air cleaner 53 has vbeen eliminated in the embodiment shown in Fig. 4,

and the intake pipe 52 is connected by a pipe 6| to tank TV. Thus, during normal operation of the pump 6|) air is Withdrawn from the tank TV, and such air, after passing through the pump 60 is discharged to atmosphere through the discharge pipe 29A, which differs from the pipe 29 of the other embodiment in that it is terminated at 62.

When the pump El) is thus utilized to produce vaccum or low pressure in the tank TV, the pumping action of the pump 6U is suspended when the pressure within the tank TV has reached the desired low level, and this may be accomplished under the present invention by unloading the pump in substantially the same manner as in the previously described embodiment. Hence when the pumping action is to be suspended, the valve 3| is closed, thereby to cut off the flow of air through the inlet passage 2| and the intake valve 22. When this occurs, the production of vacuum or reduced pressure in the heads of the cylinders serves through the connection 55 to correspondingly reduce the pressure in the crank case, and hence iiow of oil from the crank case past the pistons and into the cylinder heads is prevented.

The requisite operation of the valve 3| is attained through means that are similar to the means used in the other embodiment of the invention, but the functioning of such means is reversed so as to close the valve 30 in response to reduction of pressure in the tank TV. Thus a pipe 63 is extended from the tank TV and is connected to a pressure chamber 48A, this pressure chamber 48A being formed by a rigid casting, 45A that is concave upwardly and which has a diaphragm 41A secured across its upper concave face by means such as Va clamping ring 64. The diaphragm 41A has a connecting rod 50A secured centrally thereto and extended down--` wardly through a packing gland 65 in the lower wall or casting 46A of the chamber 48A. The extendedlower end of the connecting rod 50A is pivoted to the arm 5| of the 1ever.L, as at 56. Thus when the pressure in the tank TV and the chamber 48A reaches the desired low pressure, the diaphragm 41A is drawn downwardly so as to rotate the lever L in a counterclockwise direction and close the valve 3|. This unloads the pump -BII as hereinbefore described. When the pressure in the tank TV increases above a predetermined 4level as determined by the adjustment of the spring 42, this spring acts to open the valve 3|, and the pump 60 again becomes active to reduce the pressure in the tank TV.

From the foregoing descriptionv it will be apparent that the presentinvention enables air pumps, compressors, and the like to be unloaded in an efllcient and practical manner during continuous operation thereof, and this unloading is effected in such a way that flow of lubricant past the pistons and into the pump head is prevented.

Such control of the oil flow or distribution insures w'here a pump is used as a compressor the compressed air output will be free from oil or oil mist. In atta ing this result the equalization of air pressur s on opposite sides of` each piston prevents ilow of oil through the cylinders and into the pump head, while the rotating anti-friction bearing at one end of the crank case serves to remove any oil mist from such air as is withdrawn from the crank case during an unloading period.

It will also be evident that the present inven understood that these are capable of variationA and modication and I therefore do not wish to be limited to the precise details set forth but desire to alailnmyself of such changes and alterations as fall within the purview of the following claims.

I claim: l

1. In a pump, a cylinder block having a cylinder formed therein, a piston in said cylinder, a sealed crankcase associated with said block at one end of said cylinder, a crankshaft in said crankcase and operatively connected with said piston to reciprocate the same, a cylinder head closing the other end of said cylinder and cooperating therewith to form a compression chamber, said cylinder head having intake and discharge ports therein, check valves controlling said ports, means providing an inlet passage connected tov said inlet port, means providing discharge pas-1 sage connected to said discharge port, an unloading Valve disposed in said inlet passage in spaced relation to said inlet port and operable when closed to prevent iiow of fluid through said inlet passage to said inlet port, and means operable as an incident to the closure of said unloading valve to substantially equalize pressure conditions in said crankcase with pressure conditions in said chamber during the period of closure of said unloading valve.

2. In an air pump, Ypiston and cylinder pumping means providing a compression chamber with valved inlet and outlet ports, means providing inlet and discharge passagesA associated respectively with said valved inlet and outlet ports, a sealed crank case associated with said pumping means and having a crankshaft therein drivingly connected with said pumping means, an unloading valve disposed in said inlet passage in spaced relation to said inlet port and operable when closed'to prevent flow of fluid through said inlet passage 'to said inlet port, and means affording an equalizing duct connected between said crankcase and said inlet passage at a point located between said unloading valve and said inlet port so that said pumping means withdraws air from said crankcase and reduces the pressure in said crankcase when said unloading valve is closed.

3. In an air pump, piston and cylinder pumping means providing a compression chamber with valved inlet and outlet ports, means providing inlet and discharge passages associated respectively with said valved inlet and outlet ports, a sealed crank case associated with said pumping means and having a crankshaft therein drivingly connected with said pumping means, an unloading valve disposed in said inlet passage in spaced relation to said inlet port and operable when closed to prevent flow of fluid through said inlet passage to said inlet port, and means operable by said pumping means when said unloading valve is closed to withdraw air from said crankcase and thereby reduce the pressure in said crankcase.

4. In a pump, a cylinder block having a cyl-v inder formed therein, a piston in said cylinder,

a sealed crankcase associated with said block at one end of said cylinder, a crankshaft in said crankcase and operatively connected with said piston to reciprocate the same, a cylinder head closing one end of said cylinder and cooperating therewith to form a compression chamber, said cylinder head having intake and discharge ports therein, check valves controlling said ports, means providing an inlet passage connected to said inlet port, means providing discharge passage connected to said discharge port, an unloading valve disposed in said inlet passage in spaced relation to said inlet port and operable when closed to prevent vflow of fluid through said inlet passage to said inlet port, and means affording communication between said crankcase and said inlet passage between said inlet port and said unloading Valve to substantially equalize pressure conditions in said crankcase with pressure conditions in said chamber when said unloading valve is closed.

5. In a pump, a cylinder block having a cylinder formed therein, a piston in said cylinder, walls affording a sealed crankcase associated with said block at one end of said cylinder, a crankshaft in said crankcase and operatively connected with said piston to reciprocate the same, bearing means for said crankshaft including at least one antifriction bearing supporting said crankshaft in a wall of said crankcase, a cylinder head closf ing one end of said cylinder and cooperating therewith to form a compression chamber, said cylinder head having intake and discharge ports therein, check valves controlling said ports, means providing an inlet passage connected to said inlet port, means providing discharge passage connected to said discharge port, an unloading valve disposed in said inlet passage in spaced relation to said inlet port and operable when closed to prevent flow of fluid through said inlet passage to said inlet port, and an equalizng duct connected at one end to said inlet passage between said inlet port and said unloading valve and connected at its other end to the interior of said crankcase through said anti-friction bearing to thereby withdraw air from the crankcase through said bearing and substantially equalize pressure conditions in said crankcase with pressure conditions in said chamber when said unloading valve is closed. f

6. In a pump, a cylinder block having a cylinder formed therein, a piston in said cylinder, walls affording a crankcase associated with Said block at one end of said cylinder, a crankshaft in said crankcase and operatively connected with said piston to reciprocate the same, said crankshaft being extended at one end through a first wall of said crankcase and being supported in said wall by a sealed bearing, an anti-friction bearing supporting the other end of said crankshaft in a second wall of said crankcase, said anti-friction bearing affording spaces between the elements thereof through which air may pass into or out of said crankcase, a cylinder head closing one end of said cylinder and cooperating therewith to form a compression chamber, said cylinder head having intake and discharge ports therein, check valves controlling said ports, means providing an inlet passage connected to said inlet port, means providing discharge passage connected to said discharge port, an unloading Valve disposed in said inlet passage in spaced relation to said inlet port and operable when closed to prevent flow of fluid through said inlet passage to said inlet port, an equalizing duct connected at one end to said through said duct.

'7. In a vpumping system, a pump comprising piston and cylinder pumping means providing a compression chamber with valved inlet and outlet a ports, means providing inlet and discharge passages associated respectively with saidY valved inv let and outlet ports, a sealed crankcase associated with said pumping means land having a crankshaft drivingly connected" with said pumping means, an unloading valve, disposed in said inletv passage in spaced relation'to said .inlet port and operable when closed to-prevent flow of fluid through said inlet. passage to said inlet port, means anording an equalizing duct connected at one end to said crankcase and at its other end to said inlet passage at a point located between said unloading valve and said inlet port so that said pumping means withdraws air from said crankcase and reduces the pressure in saidcrankcase when said unloading valve is closed, a closed tank. a connection between said tank and one-of said passages whereby operation of said pumping means acts to change the pressure in said tank in a predetermined sense, and pressure operated means subjected to the pressure in said tank and operable when said pressure is varied in said predetermined sense to a predetermined value to close said lunloading valve.

8. In a pumping system, a pump comprising piston vand cylinder pumping means providing a compression chamber with valved inlet and outlet ports, means providing inlet and vdischarge passages associated respectively with said valved inlet and outlet ports, a sealed crank case associated with said pumping means and having a crankshaft therein drivingly connected with said pumping means, an unloading valve disposed in said inlet' passage in spaced relation to said inlet port and operable when closed to prevent flow of fluid through said inlet passages to said inlet port, means affording an equalizing duct connected at one end to said crankcase and at its other end to said inlet passage at a point located between said unloading valve and said inlet port so that said pumping means withdraws air from said crankcase and reduces the pressure in said crankcase when said unloading valve is closed,`

9. In a pumping system, a pump comprising piston and cylinder pumping means providing a. compression chamber with valved inlet and out-,

let ports, means providing inlet and discharge f passages associated respectively with said valved inlet and outlet ports, a sealed crank case associated with said pumping means and having a crankshaft drivingly connected with said pumping means, an unloading valve disposed in said inlet passage in spaced relation tosaid inlet port and operable when closed to prevent flow of fluid through said inlet passage" to said inlet port, means anording an equalizing duct connected lat one end of saidcrankcase and at its other end to said inlet passage at a point located between said unloading valve and said inlet port so that said pumping means withdraws air fronti said crankcase andreduces the pressure in said crankcase'. when said unloading valve is closed, a closed tank, a connection between said tank and said inlet passage whereby operation of said pumping means acts to withdraw air from said tank to decrease the pressure in said tank, and pressure operated means subjected to the pressure in said tank and operable when said pressure is lowered in said tank to a predetermined value to close said unloading valve.

10. In a pumping system, a pump comprising piston and cylinder pumping means providing a compression chamber with valved inlet and outlet ports, means providing inlet and discharge passages associated respectively with said valved inlet and outlet ports, a sealed crankcase associated with said pumping means and having a crankshaft therein drivingly connected with said pumping means, bearings means for said crankinlet port and operable when closed to prevent flow of fluid through said inlet passage to said inlet port, means affording an equalizing duct connected at one end to said inlet passage at a point located between said unloading valve and said inlet port and connected at its other end to said crankcase to communicate therewith through said anti-friction bearing so that said pumping means withdraws air from said crankcase through said anti-friction bearing' means so as to vremve oil and mist from such air and by the withdrawal of such air reduces the pressure in said crankcase when said unloading valve is closed, a closed tank, a connection between said tankand one of said passages whereby operation of said pumping means acts to change the pressure in said tank in a predetermined sense, and pressure operated means subjected to the pressure in said tank and operable when said pressure is varied 1n said predetermined sense to a predetermined value to close said unloading valve.

BURR W. MANTLE.

REFERENCES CITED v The following references are of record in the tile of this patent:

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